Vinegar is used in many ways in the making of ceramics. Check out this website for some of the most common ways it is used to make pottery. But I use vinegar to decorate ceramics.
Vinegar Paper (aka Microbial fiber) is a truly amazing material. Unlike other kinds of paper, which comes from plants, Vinegar paper is made by vinegar bacteria, Acetobacter xylinum. You can write or paint on it, cut it or mold it . It can be used for wound bandages. It is even cultivated and eaten in some countries like the Philippines where they call it Nata de Coco.
Painting using vinegar is a rather old art form. Look at what a few of my friends are doing. If you want to learn how to paint with vinegar, try this book